Calling device



Oct. 8, 1940. H. F. OBERGFELL 2,217,074"

CALLING DEVICE Filed Feb. 24, 1959 vmwwwm m E A Patented Oct. 8, 1940UNITED STATES CALLING DEVICE 1 Herbert F. obergfell, River Forest, Ill.,assignor to Associated Electric Laboratories, Inc., Chicago, 111., acorporation of Delaware Application February 24, 1939, Serial No.258,241 3 Claims. (o1. ire- 90) The present invention relates to callingdevices of the type employed in automatic telephone systems and, moreparticularly, to an improved arrangement for reducing the amount ofnoise ordinarily produced by a calling device incident to the operationthereof.

One such arrangement for reducing the amount of noise ordinarilyproduced by a calling device incident to the operation thereof isdisclosed and claimed in U. S. Patent No. 2,068,700, Seth Peterson,granted January 26, 1937, the calling device in which the noise reducingarrangement there disclosed is incorporated being of the type disclosedand claimed in U. S. Patent No. 1,642,822, Herbert F. Obergfell, grantedSeptember 20, 1927.

Briefly, the calling device disclosed in the above-mentioned Obergfellpatent comprises a finger dial which is variably rotatable in accordancewith the different digits to be dialed and a member attached theretocarrying a pivotally mounted pawl. Associated with the pawl is'acooperating ratchet wheel having a number of teeth spaced apart byintervening notches. The ratchet wheel is associated with a gear wheelwhich drives a suitable impulse sending mechanism. When the finger dialis rotated away from its normal position, the pawl is rotated over thesuccessive teeth and notches of the ratchet wheel, the number of teethover which the pawl is rotated being dependent upon the digit dialed.When the finger dial is released, it is returned to its normal positionby an associated driving spring at a substantially constant ratecontrolled by an associated governor. At the beginning of the returnmovement of the dial, the pawl engages the then over a given number ofratchet teeth aspreviously noted, and being urged by an associatedspring toward the ratchet wheel, forcibly drops from the high points ofthe teeth of the ratchet wheel into the succeeding notches of theratchet wheel causing a clatter or clicking noise which is quitenoticeable, especially if the dialing speed is increased. This clatteror clicking noise is objectionable in that it is quite annoying to aperson operating the calling device.

The arrangement for reducing the amount of noise ordinarily produced bythe calling device incident to the operation thereof, as describedvabove, which is disclosed'in the above-mentioned Peterson patent,comprises a spring having one end thereof fixed to the pivotally mountedpawl and the otherend thereof cooperating therewith a pin carried by themember upon which the pawl is pivotally'mounted. The construction andarrangement of the'pawl, the mounting member and cooperatingspringandpin are such that the spring opposes pivotal movement ofthepawl into the notch disposed between two adjacent teeth oi the ratchetwheel when the pawl is moved partially into the notch, thereby topreventthe pawl from striking the bottom of the notch.

While the arrangement for reducing the amount of noise ordinarilyproduced by a calling device incident to the operation thereof,disclosed in the previously-mentionedPeterson patent is entirelysatisfactory in operation, it is somewhat more expensive to manufacturethan is desirable. Moreover, the elements thereof must be carefullypositioned and adjusted during manufacture in order to render thearrangement effective for the purpose intended.

Accordingly, it is an object of the present invention to provide animproved arrangementfor reducing the amount of noise ordinarily producedby a calling device incident to the operation thereof, whicharrangement, is of simple and rugged construction and which iseconomical to manufacture. v

In general, the object set forth above is attained in accordance withthe present invention by providing in a calling device comprising amechanism including a ratchet having a number of teeth-spaced apart byintervening notches, a cooperating pawl, and means including a dial foroperating the pawl and ratchet; means for reducing the amount, of noiseordinarily produced as the pawl is rotated over successive teeth andnotches of the ratchet, which means comprise a spring carried by thepawl and adapted to engage successive teeth and notches'of the ratchet.The spring is so constructed andarranged that a force is exerted therebyupon the pawl as the pawl approaches the ratchet, thereby to cushionthemovement of the pawl toward the ratchet as the pawl passes over atooth and descends in the succeeding notch of the ratchet. Moreparticularly, the ratchet-engaging portion of the 3 for reciprocalmovement therein. Also, the pawl and the ratchet are so constructed andarranged that when the pawl exerts a driving force upon the ratchet thepawl is moved against the force exerted thereupon by the spring intodirect driving engagement with an adjacent tooth of the ratchet.

The novel features believed to be characteristic of the invention areset forth with particularity in the appended claims. The invention, bothas to its organization and method of operation, together with furtherobjects and advantages thereof, will best be understood by reference tothe following specification taken in connection with the accompanyingdrawing, in which Figure 1 is a plan view of a calling device, thefinger dial being removed, including an arrangement for reducing theamount of noise ordinarily produced thereby incident to the operationthereof and embodying the present invention; Fig. 2 is an enlargedfragmentary plan view of the pawl and ratchet mechanism incorporated inthe calling device shown in Fig. 1; Fig. 3 is an enlarged fragmentaryplan view of the ratchet-engaging end of the pawl of the mechanismshowing the ratchet-engaging spring mounted thereon in normal position;Fig. 4 is an enlarged side elevational view of the pawl and theratchet-engaging spring taken in the direction of the arrows44 in Fig.2; and Fig. 5 is an'enlarged plan view of, the

ratchet-engaging spring disassociated from the a Referring now,,moreparticularly, to Figs. 1 and 2 of the drawing there is illustrated acalling device embodyingan arrangement for reducing the amount of noiseordinarily produced thereby incident to the operation thereof, which isconstructed and "arranged in accordance with the present invention. Thecalling device there shown is of the type of thatdisclosed in thepreviouslymentioned Obergfell patent and comprises a rotatable plate IIIhaving a raised hub I I upon which a finger dial, not shown, having acentrally disposed opening therein is adapted to fit, thefinger dialbeing held in place by a screw, not shown, threadedv in a tappedholeprovided in the hub I I. A pawl I2 is pivotally mounted on the plateI U by a pivot pin I3 and has a toothed or ratchet-engaging portion orend I4, which is urged in a clockwise direction about the pivot pinI3-by a spring I5 extending between a stud I6 carried by the plate IIIand an arm II provided on the pawl I2. One end of thespring I5 is fixedto the stud I6 and the other end thereof is fastened in an opening I8provided in the arm I1. A rotatable ratchet wheel I 9 mounted concentricwith the axis of the huh I I is operatively associated with, the pawlI2, the.

ratchet wheel I9 being provided with a number of teeth 20 spaced apartby intervening notches 2i. -Also operatively associated with the ratchetwheel I9 is a driving gear, not shown, which is operatively associatedwith an impulse sending mechanism, not shown, which is operative tocause impulses corresponding to the various digits to be transmitted.

As best shown in Figs. 2 to 5 inclusive, a ratchetengaging spring 22 iscarried by the pawl I2, the spring 22 having an outwardly extending and23 and a free end 24. Thespring 22 is arranged on the outside of thepawl I2 and the outwardly extending end 23 thereof projecting through anopening 25 provided in the body portion of the pawl I2, the extremeouter end of the outwardly projecting end 23 thereofbeing bent over intofrictional engagement with the body portion of the pawl I2. Theratchet-engaging end I4 of the pawl I2 is provided with a bifurcation orslot 26 therein in which the free end 24 of the spring 22 is disposed,The free end 24 of the spring 22 has a return-bent configuration, thegeneral outline of which is similar, but slightly larger than theoutline of the ratchet-engaging end of the pawl I 2. The body portion ofthe spring 22 is urged into engagement with the adjacent outside surfaceof the pawl I2 and the forward portion of the free end 24 thereofprojects through the slot 26 provided in the ratchet-engaging end I4 ofthe pawl I2 into engagement with the ratchet wheel I9 associated withthe pawl I2. The spring 22 is so constructed and arranged that the freeend 24 thereof engages the ratchet wheel I9 thereby to cause the spring22 to exert a force upon the pawl I2 tending'to rotate the pawl in acounter-clockwise direction about the pivot pin I3. Thus, the forceexerted upon the pawl I2 by the spring 22 opposes the force exertedthereupon by the spring I5.

In the operation of the calling device, when the finger dial is inplace, thefinger dial is rotated in a clockwise direction about the axisof the hub II in the usual manner in accordance with the digit to betransmitted. As the finger dial is rotated in the clockwise direction,the plate I0 is also rotated in the clockwise direction due to theengagementjbetween the finger dial and the hub II of the plate ID. Therotation of the plate I0 in the clockwise direction causes the pawl I2carried thereby to slip with respect to the associated ratchet wheel I9.Accordingly, the ratchet wheel I9 remains stationary while'the pawl I2is rotated in the clockwise direction. As the pawl I2 is rotated in thedirection indicated, the ratchet-engaging end I4 thereof, rides up oneof the teeth 20 of the ratchet wheel I! and then falls into thesucceeding notch 2I of the ratchet wheel under theurgeof the spring I5,this movement of the pawl being repeated a number of times dependingupon the digit dialed.

Disregarding, for the present, the operation of the ratchet-engagingspring 22, each time the ratchet-engaging end I4 of the pawl I2 fallsoff of one of the teeth 20 of the ratchet wheel I9 into the succeedingnotch 2I of the ratchet wheel, a decided click is ordinarily producedwhen the ratchet-engaging end I4 ofthe pawl I2 engages the bottom of thenotch 2I. Thus, a series of clicks are ordinarily producedincident tothe rotation of thepawl I2 in the clockwise direction, the number ofclicks ordinarily produced depending upon the digit dialed.

The ratchet-engaging spring 22 constitutes means for reducing the amountof noise ordinarily produced by the calling device incident to theoperation thereof and, more particularly, means for minimizing theclicking noise produced by the ratchet-engaging end I4 of the pawl I2when it falls into one of the notches 2| of the ratchet wheel I9.Considering now the operation of the pawl and ratchet wheel mechanism,as disclosed, including theoperation of the ratchet-engaging spring 22carried by the pawl I2, as the ratchetengaging end I4 of the pawll2rides up'one of the teeth 20 of the ratchet wheel I9, the free end 24 ofthe spring 22 is forced further into the slot 26 provided in theratchet-engaging end I4 of the pawl I2, thereby to cause the spring 22to exert a force upon the pawl I2 in opposition to the force exertedthereupon by the spring I5. At the instant the ratchet-engaging end I4of the pawl I2 rides 011' of the tooth'20 of the ratchet wheel I9 intothe succeeding notch 2| of the ratchet wheel 49, the free end 2 1 of thespring 22 disengages the associated tooth 20 of the ratchet wheel l9 andmoves out'of the slot 26 provided in the ratchetengaging end M of thepawl l2 into a position in advance of the ratchet-engaging end ll of thepawl l2. The spring 15 then rotates the pawl 12 in a clockwise directionthereby to cause the free end 24 of the spring 22 to engage the bottomof the associated notch 2| of the ratchet wheel I9, whereupon the freeend 24 of the spring 22 is forced into the slot 26 provided in theratchetengaging end l4 of the pawl I2 in order to exert a force upon thepawl l2 in opposition to the force exerted thereupon by the spring l5.The force exerted upon the pawl l2 by the spring 22 in opposition to theforce exerted thereupon by the spring I5, prevents the ratchet-engagingend H of the pawl l2 from striking the bottom of the associated notch 21of the ratchet wheel l9, thereby to eliminate the clicking which isordinarily produced incident to the engagement of the ratchet-engagingend M of the pawl l2 and the bottom of the assos ciated notch 2| of theratchet wheel I9.

From the foregoing, it is apparent that the ratchet-engaging spring 22prevents the clicking noise ordinarily produced incident to theoperation of the calling device due to the cushioning action this springexerts upon the movement of the pawl l2 toward the associated ratchetwheel I9.

After the finger dial has been rotated in the V clockwise direction toits final position it is released, whereupon a spring, not shown, causesthe plate ID to be driven in the counter-clockwise direction back to itsnormal position. When a force is exerted upon the plate In, the forwardedge of the ratchet-engaging end [4 of the pawl l2 engages the thenadjacent tooth 20 of the ratchet wheel IS in order to cause an operatingforce to be exerted between the pawl l2 and the associated ratchet wheel19, whereupon the ratchet wheel [9 is driven in the counter-clockwisedirection in order to cause the driving gear associated therewith tooperate the impulse sending mechanism. The pawl l2, the associatedratchet wheel 19, and the ratchet-engaging spring 22 are so constructedand arranged that when moved into the slot 26 provided in the ratchetengaging end of the pawl 12.

In assembling the calling device, the ratchetengaging spring 22 ispre-formed as previously noted and then placed upon the associated pawl12 as previously explained. The extreme outer end of the outwardlyprojecting end 23 of the ratchet-engaging spring 22 is then bent over inorder, frictionally, to engage the body portion of the pawl (2 aspreviously noted. The subassembly, comprising the pawl l2 and theratchet-engaging spring 22, is then assembled into the calling device ina well-known manner. When the sub-assembly is thus assembled into thecalling device, the ratchet-engaging spring 22 is so positioned andarranged, without further adjustment thereof, that the clicking noiseordinarily produced incident to the operation of the calling device iseliminated as previously explained. I

In view of the foregoing, it is apparent that an improved arrangementfor reducing the noise ordinarily produced by a calling device incidentto the operation thereof is provided, which arrangement is of simple andrugged construction and which is economical to manufacture. I

While there has been described what is, at present, considered to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein, and it is contemplated tocover in the appended claims all such modifications as fall within thetrue spirit and scope of the invention.

What is claimed is: I

1. In a calling device provided with a mechanism including a ratchethaving a number of teeth spaced apart by intervening notches, acooperating pawl having a recess therein adjacent the ratchet-engagingportion thereof, and means including a dial for operating said pawl andsaid ratchet; means for reducing the amount of noise produced as saidpawl is rotated over successive teeth and notches of said ratchet, saidlastmentioned means comprising a spring having one of its ends fixed tosaid pawl and the other of its ends free, the free end of said springbeing disposed in the recess in said pawl and adapted for reciprocalmovement therein into engagement with the successive teeth and notchesof said ratchet, said spring being so constructed and arranged that thefree end thereof is moved into the recess in said pawl as theratchetengaging portion of said pawl approaches said ratchet, thereby toexert a force upon said pawl in order to cushion the movement of saidpawl toward said ratchet as said pawl passes over a tooth and descendsinto the succeeding notch of said ratchet, said pawl and said ratchetbeing so constructed and arranged that when said pawl exerts a drivingforce upon said ratchet the free end of said spring is moved into therecess in said pawl and said pawl is moved against the force exertedthereupon by said spring into direct driving engagement with a tooth ofsaid ratchet.

2. In a calling device provided with a mechanism including a ratchethaving a number of teeth spaced apart by intervening notches, acooperating pawl having a recess therein adjacent the ratchet-engagingportion thereof, and means for operating said pawl and said ratchet;means for reducing the amount of noise produced as said pawl is rotatedover successive teeth and notches of said ratchet, said last-mentionedmeans comprising a spring having one of its ends fixed to said pawl andthe other of its ends free, the free end of said spring being disposedin the recess in said pawl and adapted for reciprocal movement thereinand for engagement with the successive teeth and notches of saidratchet, said spring being so constructed and arranged that the free endthereof is moved into the recess in said pawl as the ratchet-engagingportion of said pawl approaches said ratchet, thereby to cushion themovement of the last-mentioned portion of said pawl as saidlast-mentioned portion thereof passes over a tooth and descends into thesucceeding notch of said ratchet.

3. In a calling device provided with a mecha nism including a ratchethaving a number of teeth spaced apart by intervening notches, acooperating pawl having a bifurcated ratchetengaging portion, and meansfor operating said and notches of said ratchet, said spring being soconstructed and arranged that the free end thereof is moved into thebifurcation in the ratchet-engaging portion of said pawl as thelast-mentioned portion thereof'approaches said ratchet, thereby tocushion the movement of the last-mentioned portion of said pawl as saidlastmentioned portion thereof passes over a tooth and descends into thesucceeding notch of said ratchet.

. HERBERT F. OBERGFELL.

